MGK Pool Service

Inground Liner Replacement

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Inground pool liners can last up to 25 or more years. The average pool owner should only have to replace their pool liner once. To get the full life out of your liner, you have to keep chemicals within normal ranges, and have it “installed properly”.

To handle any problems that may arise during the installation, do your best to hire an experienced installer. By reading this: “inground liner replacement guide”, you should be able to ask your installer some informed questions, and compare apples to apples.

Choosing A Liner

Your installer should be able to supply you with samples from a few quality manufacturers. You want a liner made from virgin vinyl, not one that uses any recycled materials. Liners made with recyclables are less pliable, affecting the durability of the liner, and it’s ability to handle seasonal temperature changes.

Before you order a new liner, you will want to decide on any changes to the pool shape. These include: The addition of stairs; change in the slope angle, or pool depth. Many homeowners are eliminating deep ends for safety.

Liners come in a variety of exciting new colors and patterns. There are textured materials that can be embossed on steps for better traction. You will find all manufacturers offer thicker mils for the walls, pool bottom, or steps, depending on your needs. A 27 or 28 mil side wall is the most common upgrade.

Pool Liner Warranties

Most people misunderstand pool liner warranties. They are pro-rated, which means you get less and pay more the longer the liner is in your pool. I would like to point out that in my personal experience with 7 or 8 major manufacturers, and at least 2000 liner installations over a 40 year career, 1 out of 70 liners have a problem during the initial installation, 1 out of 700 liners will have a failure in the second year, and 1 out of 2000 will have a failure in the third year. New high quality liners don’t fail often, they may get damaged, but it most likely won’t be due to a manufacturer defect, which is all that is covered.

Few if any liner replacements are credited with a manufacturers warranty after the fourth year, so don’t purchase a liner based on a “warranty gimmick”. I would love to hear from pool owners that have successfully used a warranty from a manufacturer. Anyone trying to get a higher price for a job because of warranty, is either uninformed or unscrupulous.

Draining Pool Water

When the liner arrives it is time to take the water out of the pool. You may choose to store the water on site, or discard it. If you discard it, be sure not to raise your ground water table, flood your neighbor, or pump into a street or basin not allowed by your town, make good decisions.

Our big concern when we pump out a pool is the groundwater table level. If it is higher than the pool bottom, it can cause some damage and extra work.

If you do have ground water and the pool was installed at a time of the year when the excavator hit water, then you probably have a ground water pipe going into crushed stone under your pool. If this pipe can be located, the groundwater can be pumped down and the potential problem eliminated. If not, there are a few other options. Groundwater can mean extra costs, so be sure to ask your installer if there are extra fees to handle this groundwater issues.

Pool Walls Collapsing Potential

We installers have all heard stories of pool walls collapsing when a pool is drained. I have only had this happen on a wood walled pool, but have seen steel walled pools move. If your walls are not perfectly straight to begin with, then you may not have a cement collar around the outside of your pool walls, and braces. If this is a possibility, I would wait till a dry period to relieve the weight of the backfill on your pool walls, I would prepare well and do the job as quickly as possible, and avoid any extended rain forecasts.

Pool Bottom

I always hope that your pool bottom is vermiculite. This is a cement product that can be easily cleaned and patched. If the vermiculite was installed thin or has been exposed to groundwater for extended periods, then additional repairs may be necessary.

Older pools may have a sand bottom. This will be displaced when the liner is removed, and will need to be re-troweled at an additional cost. The other option is to cover it with vermiculite, making a permanent bottom.

My least favorite pool bottom to work with is stone dust. It works well for the initial installation, but the sharp pieces of stone that make up stone dust, lift up as the finer pieces  that make up stone dust settle. The sharp stones adhere to the liner as it’s being pulled out. this causes a residual of sharp stone chips that will always cause a premature failure of the pool liner.

The only option is to skim coat the pool bottom with vermiculite. If anyone tells you otherwise, you tell them you are going to inspect the bottom for stone particles before you let them put in the new pool liner. Too many people have learned this lesson the hard way.

The next most common pool bottom is grout. This is a sand and cement mix that is formed dry, then carefully moistened and allowed to harden into porous cement. These bottoms normally need some work, and may need a skim coat so as to lock down the coarse grains of sand that are used as the aggregate or bond for the cement.

Unless you are positive of your pool bottom type, you need to be aware of the options, and know what to expect for possible additional charges. Nobody likes surprises, and I hate to give bad news, but quite often we are not given enough clues to guarantee what your pool bottom is, until the pool is drained. There are many installers that will just slap a liner in any pool, and take the money and run.

Now Let’s Get To Work

The liner is here and the pool is empty. We cut the old liner into strips and fold it for removal. the groundwater is taken care of and it’s time to prepare the pool for relining.

  1. We remove all the face plates and gaskets and pull the light from the deck box connection, and remove it.
  2. We inspect the walls for damage, or rust through. We can install steel or aluminum plates to repair rotted skimmers and returns.
  3. We test each underground pipe to identify any buried plumbing failures.
  4. We visually inspect the light niche, skimmer box, main drain, and stairs sections to find any cracks, gasket failures, or needed repairs.
  5. The fiberglass or plastic stair section is cleaned with our special 2 step process, and the step section is covered with our stair plate to prevent damage.
  6. Steel or aluminum staircase rods are cut out and the holes are caulked.
  7. The liner track is cleaned and sized to insure the new liner will stay in place. extra care is given to the stair corners.
  8. The entire pool wall is scraped to remove loose dirt, rust, and burs.
  9. The liner track and the pool walls are washed down with a high pressure nozzle.
  10. The liner track is blown out and the coping is caulked to the pool wall. Any wall seam or stair seam is also caulked. This seals all cracks and gives us a good vacuum when we set the liner. It also helps keep out moisture which causes corrosion.
  11. We apply rust restore to any badly rusted spots, and then put a rust inhibitive paint.
  12. The pool bottom is carefully washed and vacuumed to remove all debris. this step is repeated as necessary.
  13. The gaskets are replaced wherever needed.
  14. The wall foam is installed.
  15. The liner is set into place and vacuum formed to remove wrinkles.
  16. New stair rods are installed when needed.
  17. A set of new face-plates and gaskets are installed. We carry an extensive supply of stainless steel screws, so we make sure that all old stripped screws are replaced with the proper stainless screws.
  18. The pool is refilled with water and the filter is started and inspected.
  19. We pick up and remove all trash

Measuring And Work Behind The Liner

To avoid over-stretching your liner on the walls or in the corners, your pool has to be properly measured, and then your new liner has to be properly set. These are two of the most important elements.

If your liner is over stretched in any area, it will be thin, susceptible to leaks and premature failure. In order for your liner to fit like a glove, and be free of wrinkles, your pool has to be measured well, and it has to be evenly stretched “a little” while being properly set.

To be set properly, you have to get a good even vacuum all the way around. If you have gaps where the pool wall meets the coping, or wall seems that are leaky, your vacuum will be weak, and uneven. This will result in large air pockets in the corners (bellied corners), seams won’t be close to wall/floor intersections, and the liner will be over stretched to compensate.

Most of this article was written by my chief installer David Clapp. He has over 40 years experience installing pools and liners here in Massachusetts. He enjoys answering questions when he has time. Please ask questions in the comments below. Thank you!

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